1. Field of the Invention
The invention relates to the field of imaging, and in particular the processing of raw images or tensor images.
2. Definitions
Before further discussion, a definition of the following terms will aid in the understanding of the present invention.
The terms used in this disclosure are defined as follows unless otherwise indicated. Standard terms are to be given their ordinary and customary meaning as understood by those of ordinary skill in the art, unless expressly defined herein.
The term “raw image” is taken here to mean an image supplied by an imager (or image capture device) in the form of vectors or symmetrical matrices (not necessarily defined as positive) and intended to allow or facilitate the production of a tensor image.
Furthermore, the term “tensor” is taken here to mean a matrix of n*n numbers which is symmetrical and defined as positive. The dimension n is generally equal to 2 in the case of two-dimensions (2D) or 3 in the case of three dimensions (3D), but the invention is not limited to these two values. It relates in fact to any value of n.
Furthermore, “tensor image” is taken here to mean an image represented by a set of tensors each associated with an elementary part of a two- or three-dimensional grid. In the case of a two-dimensional (2D) grid, each elementary part is called a “pixel”, whereas in the case of a three-dimensional grid (3D) each elementary part is called a “voxel”.
As the person skilled in the art knows, tensors are mathematical objects which are frequently used in the field of imaging. This is particularly the case in the field of medical imaging, e.g. in order to analyse diffusion tensor images obtained by magnetic resonance (technology known by the English acronym DT-MRI for “Diffusion Tensor Magnetic Resonance Imaging”—diffusion tensor imaging obtained by magnetic resonance, or written more simply as DTI for “Diffusion Tensor Imaging”).
In general, “diffusion tensor” is taken to mean here the covariance matrix of a diffusion process at one point of a physical medium.